ML20151R105
| ML20151R105 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 08/05/1988 |
| From: | Cruden D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 88-385A, NUDOCS 8808120053 | |
| Download: ML20151R105 (4) | |
Text
.
e VIHOINIA I$LECTHIC AND POWHH CO)fl%NY RicnMoxn, VIHOINIA 20261 August 5, 1988 D. S Ca t: Dan
%ca 1*mansnsw?-Necs.na u United States Nuclear Regulatory Commission Serial No.
87-385A Attention: Document Control Desk NL/DJV:Juj Washington, D.C.
20555 Docket Nos.
50-338 50-339 License Nos. NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPAN_1 NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATIONS CHANGE INCREASED CONTAINMENT TEMPERATURE LIMIT Virginia Electric and Power Company letter dated March 2, 1988 requested amendments to the operating licenses for North Anna Power Station Units 1 and 2 to support operation of the units with containment average air temperatures up to 120*F.
The purpose of this letter is to provide additional information regarding the environmental qualification of electrical equipmant and the analysis of the inadvertent operation of the quench spray system as requested by the NRC Project Manager in a cor.ference call on July 20, 1988.
Environmental Oualification of Electrical Eautomen; In order to maintain the environmental qualification of electrical equipment, our letter of March 2, 1988 committed to develop appropriate periodic test procedures to monitor containment average air temperature, and to use this information to adjust equipment service lifetimes and maintenance schedules, as appropriate.
These procedures, which are currently in place, entail an evaluation of daily containment average air temperature data for comparison against an annual operating time versus containment average air temperature standard.
This evaluation will be performed at least annually.
The annual operating time versus containment average air temperature standard is provided in Attachment I to this letter.
This standard was derived using the Arrhenius methodology to determine the equivalent thermal age degradation associated with operation at different temperatures above and below 105'F.
This calculation was performed for the worst case material in safety-related electrical equipment in the North Anna containments.
Our past operating experience has shown this operating time versus temperature standard to be conservative relative to actual operation.
However, even if the standard is exceeded by a small amount during a year, the effects on service lifetimes and maintenance schedules would be small and easily managed within existing preventive maintenance and outage schedules.
OY 8808120053 880805 PDR ADOCK 05000338 I
l P
4 Inadvertent Operation of Ouench Soray System An analycis of the inadvertent operation of the Quench Spray System was performe0 as part of the analysis to support the requested amendment.
The analysis method and acceptance criteria are described in Section 6.2.6.3 of the North Anna UFSAR.
The supporting calculations for the current containment average air temperature limit of 105'F are presented on UFSAR Table 6.2-75.
This table is reconstructed in Attachment 2 to this letter to compare the current UFSAR analysis (Case 1) to the effect of increasing the allowable containment average air temperature to 120*F (Cases 2 and 3).
Case 2 assumes the same conservative initial air partial pressure of 8.6 psia as Case 1.
Case 3 assumes an initial air partial pressure of 8.9 psia which corresponds to the proposed Technical Specification limit of 9.0 psia minus an appropriate allowance for instrument uncertainty.
The results of the analysis show that there is adequate margin to the containment lower pressure limit of 5.5 psia in the event of an inadvertent quench spray actuation.
Very truly yours, s
?
cc:
U. S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 2900 Atlanta, GA 30323 Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station Commissioner Department of Health Room 400 109 Governor Street Richmond, Virginia 23219 I
i
..a A
ATTACHMENT 1 Annual Operating Time Versus Containment Average Air Temperature Standard
- Daily Peak Average Temperature Range (*F)
Number of Days 115 < T s 120 5
112 < T s 115 5
101 < T s 112 5
103 < T s 107 6
100 < T s 103 36 95 < T s 100 158 T s 95 150 i
- This standard equates to an Equivalent Arrhenius Temperature 105 F for a period of 365 days.
I
i ATTACHMENT 2 CONTAINMENT PRESSURE ANALYSIS-FOR INADVERTENT OPERATION OF QUENCH SPRAY SYSTEM Initial Containment Conditions Case 1 Case 2 Case 3 Minimum air-partial pressure (psia) 8.6 8.6 8.9 Maximum bulk air temperature (*F) 105 120 120 Final Containment Conditions Air partial pressure (psia) 7.6 7.4 7.7 Water vapor pressure (psia) 0.12 0.12 0.12
. Containment temperature (*F) 40 40 40 Minimum total pressure (psia) 7.7 7.5 7.8 Case 1 - Current UFSAR analysis Case 2 - Proposed containment average air temperature of 120*F and conservative initial air partial pressure of 8.6 psia.
Case 3 - Proposed containment average air temperature of 120*F and initial air partial pressure of 8.9 psia corresponding to proposed Technical Specification limit of 9.0 psia minus 0.1 psia for instrument uncertainty.